Why do we use CASE Statement in SQL? Give example - SQL Interview Question

 

The CASE statement is similar to the IF ELSE statement in other programming languages.  We can use this to get or show particular values based on certain conditions.

Example:

Take a table student:

id	name	gender
1	Rahul	M
2	Veronica	F
3	Raj	M
4	Preeti	F
5	Ramesh	M
6	Amit	M

Now we will be going to implement a CASE statement to get gender Male for 'M', Female for 'F', and Other if nothing is defined.

SELECT id, name, CASE WHEN gender='M' THEN 'Male'

WHEN gender='F' THEN 'Female'

ELSE 'Other'

END AS gender

FROM student;

Output Table:

id	name	gender
1	Rahul	Male
2	Veronica	Female
3	Raj	Male
4	Preeti	Female
5	Ramesh	Male
6	Amit	Male